摘要:

It is pointed out that the eikonal scheme suggests a powerful sum rule which relates the end‐on light scattering by a system ofNdielectric spheres to scattering by a single sphere. The sum rule is tested numerically for two dielectric spheres and shown to work for wide ranges of size parameter and refractive index.

ISSN:0021-8979    

DOI:10.1063/1.344540

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

An Al oxide‐GaAs (100) interface fabricated by the reactive deposition of Al into a molecular oxygen overlayer on a gallium terminated GaAs (100) surface atT=49 K is studied by synchrotron radiation photoemission. Al forms a stable oxide layer by reaction with O2until all the oxygen is consumed. Limited oxidation of surface As atoms (≊20%) is observed during the initial deposition of Al, but further Al deposition reduces the AsO bond. The well‐known exchange reaction between Al and Ga when Al is directly deposited on GaAs (100) is not observed.

ISSN:0021-8979    

DOI:10.1063/1.344541

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The formation of buried SiO2layer by high‐dose oxygen implanted into Si/Ge and Si/Si0.5Ge0.5heterostructures is studied by infrared transmission and x‐ray photoelectron spectroscopy. The results show that the Ge in the implanted region has no influence on the bonding properties of oxygen, and there exists a critical annealing temperature of about 1250 °C for all the implanted oxygen to be bonded as SiO2.

ISSN:0021-8979    

DOI:10.1063/1.344542

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The Meissner‐effect interaction of a small permanent magnet with a superconducting hollow cylinder has been investigated by solving the Laplace equation numerically using a finite‐difference method. The calculations reveal the existence of stable equilibrium configurations for a range of shapes and sizes of the cylinder. The computed magnitude of the Hooke’s law force constant is close to those measured for small magnets levitated above superconducting disks.

ISSN:0021-8979    

DOI:10.1063/1.344543

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Insitusurface sensitive photoemission spectroscopy has been used to study the evolution of the strained layer GaAs/In0.52Al0.48As heterostructure as the GaAs overlayer is grown past the critical layer thickness in sequential steps by molecular‐beam epitaxy. The variation in spectral features evident in the GaAs valence band is inconsistent with predictions of tight binding theory for strain relaxation. An analysis of the core level spectra suggests that In out‐diffusion is responsible for the valence band modification.

ISSN:0021-8979    

DOI:10.1063/1.344544

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report the transfer of 48% of the incident power from a semiconductor laser array into a diffraction‐limited beam by means of photorefractive coherent beam combination in BaTiO3, using a progressive two‐wave mixing geometry. A single‐element, photorefractive beam combiner is described which should allow the transfer of 88% of the power of a suitable array into a single diffraction‐limited beam.

ISSN:0021-8979    

DOI:10.1063/1.344545

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Absorption measurements and electron microprobe analysis are used to determine the density of Cu1+and Cu2+ions in a photorefractive KTa1−xNbxO3:Cu,V sample. Photorefractive measurements are made over a wide range of Cu1+and Cu2+concentrations, altered by a series of oxidation and reduction treatments. Diffraction efficiencies were varied by over an order of magnitude while erasure rates were varied by over two orders of magnitude.

ISSN:0021-8979    

DOI:10.1063/1.344546

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

InP polycrystals grown by the HB technique and InP single crystals grown by the liquid‐encapsulated Czochralski technique have been evaluated by photoluminescence. It was found that as the carrier concentration is decreased, the photoluminescence spectrum shows finer structures. When the carrier concentration is less than 9×1014cm−3, a strong free‐exciton peak could be observed.

ISSN:0021-8979    

DOI:10.1063/1.344547

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Minority‐carrier recombination lifetimes have been extensively measured with a noncontact laser/microwave method for metal‐dopedp‐type Czochralski silicon crystals in the temperature range from room temperature to 250 °C. The contrasting behavior of the lifetime as a function of temperature is shown for Fe‐ and Cr‐doped silicon crystals. Iron doping greatly shortens the lifetime in the entire temperature range. Although Cr doping also greatly shortens at room temperature, the degradation effect completely disappears at elevated temperatures. Doping the Na, Ni, Cu, and W shows little effect on lifetime; Na doping results in a rather higher lifetime compared with that of undoped silicon. Moreover, lifetime measurement as a function of holding time at an elevated temperature clearly distinguishes uncontaminated silicon from metal‐doped silicon.

ISSN:0021-8979    

DOI:10.1063/1.344548

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

An analysis is presented of the effect of tilt in the high‐strain‐rate pressure‐shear plate impact experiment. Normal and shear tractions and the velocity difference across the specimen are obtained from free‐surface particle velocity, tilt angle, closure direction, and impact velocity data. The effect of tilt in high‐strain‐rate pressure‐shear plate impact is shown to be small unless the velocity difference across the specimen is itself small.

ISSN:0021-8979    

DOI:10.1063/1.344549

出版商:AIP    

年代:1990

数据来源: AIP